Electrical safety-fuse.



G. MULLER.

ELECTRICAL SAFETY FUSE.

APPLICATION FILED 11011.29, 1910.

Patented Dec. 12, 191] 2 SHEETS-SHEET l.

G. MULLER.

ELECTRICAL SAFETY FUSE.

APPLICATION FILED NOV. 29, 191C,

Patented Deo. 12, 1911.

2 SHEETS-SHEET 2.

GEORG MLLER, or soHwBIscH-GMND, GERMANY.

ELECTRICAL SAFETY-FUSE.

Specification of Letters Patent.

Patented Dec. 12,' 1911.

Application filed November 29, 1910. Serial No. 594,647.

`provided with means for preventing the use of false insertion pieces suitable for too great vor too little strength of current, and differs from known safety fuses by the improvement of the contact at the top of the plug and of the cap in such manner that these contact parts determine the limits of current strength permissible in each case. For this purpose the contact piece of the cap is lengthened into a sleeve which is passed over the central contact bolt, and at the same time effects ,the quick iixing of the safety fuse by the gripping of a screw-threaded nut fitted into the bore of the plug, and a bayonet joint or other suitable quick closing connection into the correspondingly formed contact bolt. The production of an intimate contact in the upper part of the plug is effected by letting a box with spring sides into a recess in the said upper part of the plug, which sides grasp yieldingly but closely a ring on the aforesaid sleeve. The closing of the current is not produced alone by the upper and lower contacts, but also by the above mentioned quick closing connection and guide socket and is equally distributed over the separate component parts of the safety fuse as has been heretofore possible.

In the accompanying drawings Figures 1, Y

2 and 2 are sectional views of a safetyefuse constructed iii accordance with my invention. Figs. 3 to 7 are detail views of same, and Figs. 8 to 14 show modifications.

As shown in Figs. 1 and 2 there is Xed in the middle of the base a a screwed" bolt h over which is passed the plug ZJ furnished with a central bore. a metallic bushing f which serves as a guide socket, andwhich carries at its lower part a partly cut away screwed projection Z. The metal rings c, c at the bottom of the plug b and on base a form the lower or foot contact in the usual known way, while the upper or head contact, connected with the lower contact by the fuse wire consists of a box This bore is lined with` Z with slit spring sides i let into the upper recess of the plug into which boX the contact piece j of the cover e enters. The contact piece y' forms a ring at the upper part of the sleeve g Xed to the cover e, which sleeve is, in some cases, furnished with a tongueml the breadth and depth of which fits the cut away part of the screw threadZ (F ig. 2a). For this and the tongue m may be substituted a bayonet joint or any other suitable quick closing connection.

For the purpose of placing the plug b in the base a it is, in the example shown, first passed with its central bore and screw thread Z over the screw bolt It, which is possible without gripping of the thread of Z in that of h, as the cut-away part of Z allows a suiiicient side movement of Z opposite to L. Thereupon the sleeve g, fixed to the cover e, is guided so far into the space between the metal bush or guide socket f and the bolt h, that the said space is completely illed, and the ring j is clamped :tast between the. spring sides c' of the boX (Z, so that the circuit is closed through the rings c, the fuse wire c, the upper contact eZ, e', j, and the sleeve g to the bolt L direct on the one hand and on the other hand over the guide socket f and the screw-thread Z. The grip of the screwthread Z in the thread of the bolt h is at the same time assured by the entry of the tonguepiece m into the cut-away part of the nut screw-thread Z. If the tongue m fails the placing of the sleeve g in the guide socket f suiiices to center it and therefore to eiect the gripping of the screw-threads. The tightening up of the screw connection Z, h is now effected by turning the plug Z).

In Fig. 10 the invention is shown applied to a safety-fuse the cap of which has, .as usual, a flat contact. The socket projection g on the handle g isfurnished with a tongue m', and is placed in the space between the lined bore of the cover and the screwthreaded bolt ZL for closing the connection, whereby'the grip of the screw-threads and the tightening up are effected in the same way as previously described.

The means for preventing the use of wrong insertion-pieces according to the invention -may be varied considerably, but they must be so arranged that they correspond with the sleeve g making the contact for the upper side of the plug.

In Figs. 3 to 6 are shown, by way of eX- ample, plugs and insertion-pieces for 30, 20, 10 and 6 amperes. Tension and current strength are for each safety plug suitably marked, as shown in Fig. 7, on the upper sidenof the cover connected with the sleeve g and contact j, and forming one piece with them, in order to avoid confusion heretofore present. -As shown in Figs. 3 to 6 the plug-socket f and the sleeve g are of diferent lengths for t-he different safety-fuses, so that for example in a plug for 6 amperes an insertion sleeve for 30 amperes cannot be so inserted that the current circuit is closed in the contact piece al, z', j. As seeny in Figs. 4, 5 and 6 the lsleeves g, at their outer surface, and the metallic linings f in their` bores are so shaped that in any plug Z) neither a cover e with sleeve g adapted for higher nor for lower strength of current can be inserted so as to close the circuit. If for example, as shown in dotted lines in Fig. 5, an insertion piece designed for 20 amperes is put into a plu b designed for 10 amperes, the lower end ot the sleeve g comes against the screw-threaded part Z before the entrance of the contact piece j into the box i, cl is possible. It on the other hand an insertion piece designed for 10 amperes is pui` into a plug designed for 20 amperes (Fig. 4) the shoulder o of the sleeve g comes against the projection o3 of t-he guide socket fand thus prevents the closing of the current circuit at the upper part of the plug. In Figs. 8 and 9 are shown further means for effecting the same object. In this case there are used insertion-pieces g .of various depths of bore, as well as a number of adjusting screws p, p which are screwed into the upper end of the screwed bolt h. The bores of the sleeves g of various depths, and the various heights of the adjusting screws screwed into the bolts L, only allow the entrance of the contact piece j into the box Z if the screw p has the height corresponding to the depth of the bore in the sleeve g. In Figs. 8 and 9 the parts are so shown that contact is produced. If, however, the screw p of the arrangement according to Fig. 9 is put into that according to Fig. 8 the formation of a contact is prevented. The arrangement of adjusting screws is not required when, as shown in Figs. 11 and 1Q, screwed bolts zf, h2, h3, h4, h5, of various heights are arranged in the usual way. In the employment of arrangements such as those shown in Figs. 8, 9 or 11, 12 regard must also be had to the fact that by placing an insertion-piece g designed for higher adjusting screws p, p, or for higher screwthreaded bolts L to 71.5, on to screws of less height contact cannot be made if at the same time the sleeves g or the guide sockets f have different lengths, and are provided with shoulders o.

The above described devices give the further advantage of the convenient employment of the already known indicator pin on the removable plug-cover e, easily seen from outside, for indicatingthe break of the fusing wire, as shown in Figs. 13 and 14. In these gures parts e, b, h, f, g, d, and j correspond substantially to the parts denoted by the same letters in Figs. 1 and 2. In t-he plug b is inserted, parallel to the principal fusing wire 7c, a secondary wire le', to which the lower head 1 of the pin 2, placed in a recess of the plug b, is connected. This pin is pushed out, by the action of an insulated spring, on the melting of the wire, so that its end 4 projects out of an eccentrically arranged hole in the plug cover e (Fig. 13) or allows an indicator pin 8 fitted into the central bore of the cover to be pushed out by means of the lateral arm 7 (Fig. 14) .so that rupture of the fusing thread is thereby indicated.

I claim- 1. An electrical safety fuse comprising,

in combination, a plug having a central bore, a central contact bolt passing through said bore, a metallic guiding socket in said bore having a projection adapted to contact with said central bolt, a cap for said plug, a metallic conducting member connected with said cap adapted to be guided between said metallic guiding socket and said central contact bolt, and to effect a quick closing connection between the said bolt and said plug.

A 2. An electrical safety fuse comprising, in combination, a plug having a central bore, a central contact bolt passing through said bore, aunetallic guiding socket arranged in said bore having a projection adapted to contact with said central bolt, a cap for said plug, a metallic conducting member arranged in said plug adjacent said cap said metallic conducting member having electrical connections, and a metallic conducting member connected with said cap having a portion adapted to engage said first-named metallic conducting member and also having a portion adapted to be guided between said metallic guiding socket and said central contact bolt, and to effect a quick closing connection between said bolt and said plug, and at the saine time to close the circuit between said metallic conducting members.

3. An electrical safety fuse comprising, in combination, a plug having a central bore, a central contact bolt passing through said bore, a metallic guiding socket arranged in said bore said socket having a projection partially cut-away and adapted to contact with said central bolt, a cap for said plug, a metallic conducting member connected with said cap and being adapted to be guided between said guiding socket and said central contact bolt and to enter said cut- `central contact bo t passin partially cut-away and adapted to contact with said central bolt, a cap for said plug, a

metallic conducting member arranged on said plug adjacent said cap and having elec- "trical connections, and a metallic conducting member .connected with said cap and having a portion thereof adapted to engage said first-named conducting member and also having a portion adapted to be guided between said guiding socket and said central bolt and to enter said cut-away port-ion of said projection so as to effect a quick closing connection between said bolt and said plug, and at the same time to close the circuit between said metallic conducting members.

5. An electrical safety fuse comprising, in combination, a plug havi a central bore, a central-contact bolt passing through said bore, a metallic guiding socket in said bore having a projection partially cut-awayr and adapted to cont-act with said central bolt, a cap for said plug, a met-allie lconducting member arranged on said plug adjacent said cap, a metallic conducting member connected with said cap and adapted to engage said first-named metallic conducting member, and a sleeve connected with said secondnamed metallic conducting memberadapted to be guided between said guiding socket and said central contact bolt and to enter said cut-away portion of said projection,

-so as to eect a quick closin connect-ion between said bolt and said p ug, and at the same time to close the circuit between said metallic conducting members.

6. An electrical safety fuse comprising, in combmatlon, a plug having a central bore,

. a oentralcont-act bolt passing through said bore, a metallic guiding socket in said bore having a screw-threaded projection partially cut-away and adapted to contact with said central bolt, a cap for said plug, a metallic conducting member arranged on said plug adjacent said cap and having electrical connections, a metallic conducting member connected with said cap and adapted to engage said first-named metallic conducting member, and a sleeve connected with said second-named metallic conducting member `adapted to be guided between said guiding socket and said central contact bolt and to enter said cut-away portion of said pro-v jection, and to -efect a quick closing connection with said bolt and said plug, and at the same time to close the circuit between said metallic conducting members.

7. An electrical safety fuse comprising,

combination, a plug havi a central bore, a central contact bolt passlng through said bore, a metallic having a projectlon adapted to contact with said central bolt, a cap for said plu saidk lcombination, a plug having a central bore,

a cent-ral contact bolt passing through said bore, a metallic guiding socket arranged in said bore having a screw-threaded projection partially cut-away and adapted'to contact vwith said central bolt, a cap for said plug, said plug being provided with a recess adjacent said cap, a metallic boxA having springsides seated in said recess, and a metallic conducting member connected with said cap and having a portion adapted to seat in said metallic box and also having a portion adapted 4to be guided between said guiding socket and said central contact bolt, and to effect a quick closing connection between said bolt and ysaid plug, and at the same time to close the circuit between said metallic box and said metallic conducting member.

9. An electrica-l safety fuse comprising, in combination, a plug having a Central bore, a central cont-act bolt passing through said bore, a metallic guiding socket in said bore having a screw-threaded projection partially cut-away and adapted to contact with said central bolt, a cap for said plug, said plug being provided with a recess adjacent said cap, a metallicy box with spring sides seated in said recess, a metallic conducting member connected with said cap and adapted to vseat in said metallic box, and a sleeve connected with said metallic conducting member adapted to be guided between said guiding socket and said central contact bolt and to enter said cut-away portion of said projection, so as to eiect a quick closing connect-ion between said bolt and said plug, and at the same time to close the circuit between said metallic box and said metallic conducting member.

10. An electrical safety fuse comprising,

in combination, a plug having a central bore,v

a metallic guiding socket arranged in said bore, a cap Ifor said plug, said plug being provided with a recess adjacent said cap, a

in f metallic box having spring sides seated in uiding socket in said bore said recess, and a metallic conducting member connected with said cap and adapted to be grasped by the spring sides of said metallic box, said metallic conducting member also having a portion adapted to engage said guidinlg socket.

11. n electrical safety fuse comprising, in combination, a plug having a central bore, a metallic guiding socket arranged in said bore, a cap for said plug, said plug being provided with a recess adjacent said cap, a metallic box having spring sides seated in said recess, a metallic conduct-ing member connected with said cap and ada ted to be grasped by the spring sides of said metallic box, and a sleeve connected with said metallic conducting member adapted to engage said guiding socket and to close the circuit between said metallic box and said metallic conducting member.

12. An electrical safety fuse comprising, in combination, a plug having a central bore, a metallic guiding socket arranged in said bore, a cap .for said plug, said plug being provided with a recess adjacent said cap, a metallic box having spring sides seated in. said recess, a fuse wire connected with said metallic box, a metallic conducting member connected with said cap and adapted to be grasped vby the spring sides of said metallic box, an electrical terminal connected with said metallic conducting member, and a sleeve connected with said metallic conducting member adapted to engage said guiding socket and to close the circuit between said metallic box and said metallic conducting member.

13. An electrical safety fusecomprising, in combination, a plug having a central bore, a metallic guiding socket arranged in said bore said socket having a screw-threaded projection partially cut-away, a cap for said plug, said plug being provided wit-h a re- .cess adjacent said cap, a metallic box having spring sides seated in said recess, a fuse wire connected with said metallic box, a metallic conducting member connected with said cap and adapted to be grasped by the spring sides of said metallic box, an electrical terminal connected with said metallic conducting member, and a sleeve connected with said metallic conducting member adapted to engage said guiding socket and to enter the cut-away portion of said projection.

14. An electrical safety fuse comprising, in combination, a base piece, a plug arranged in said base piecesaid plug having a central bore, metallic conducting rings arranged on said base piece and on said plug adapted to contact with each other, a central contact bolt mounted in said base piece tral bolt, a cap for said plug, said plug being provided with a recess adjacent said cap, ametallic conducting member arranged in said recess, a fuse wire connected with said metallic conducting member and with said rings, a second `metallic conducting member connected with said cap and adapted to engage said first-named metallic conducting member, and also having a portionadapted to be guided between said guidin socket rand said contact bolt, so as to cise the circuit through said fuse wire and said metallic conducting members.

15. An electrical safety fuse comprising, in combination, a base piece, a plug arranged in said base piece said plug having a central bore, metallic conducting rings arranged on said base piece and on said plug adapted to contact with each other,

la central contact bolt mounted in said base piece and passing through said bore of said plug, a metallic guiding socket arranged in said bore and adapted to contact witi said ycentral bolt, a cap for said plug, said plug tween said guiding socket and said centralcontact bolt and to effect a quick closing connection between said bolt and said plug.

16. An electrical safety fuse comprising, in combination, abase piece,a plug mounted in said base piece said plug having a central bore, a central contact bolt mounted in said base piece and passing through said bore of said plug, metallic rings arranged on said plug and said base piece and adapted to make contact with each other, a metallic guiding socket arranged in said bore having a screw-threaded projection partially cut-away and adapted to make contact with said central bolt, a cap for said plug, said plug being provided with a recess adjacent said cap, a metallic -box having spring sides seated in said recess, a fuse wire connected to said metallic box and to said rings, a metallic'sleeve connected with said cap said sleeve beino provided with a ring or enlargement adapted to be grasped by the spring sides of said metallic box, and a portion of said sleeve being adapted to be guided between said guiding socket and said central contact bolt and to enter the cut-away portion of said projection, so as to effect a quick closing connection between said bolt and said plug, and at the-same time to close the circuit through said fuse Wire, said metallic box,

said ring and sleeve, and said central contact bolt, substantially as described.

17. An electrical safety fuse comprising, in combination, a plug having a central bore, a central contact bolt passing through said bore, a metallic guiding socket arranged in said bore having a projection adapted to contact with said central bolt, a cap for said plug, a metallic boX having spring sides arranged in said plug adjacent said cap, a pair of fuse wires in said plug connected with said metallic box, a metallic conducting member connected with said cap adapted to seat in said metallic box and to be grasped by the spring sides thereof, a pin in said cap electrically connected with one of said fuse wires, means adapted to force said pin outside said cap when said fuse wire is melted, and a sleeve connected with said metallic conducting member adapted to be guided between said guiding socket and said central contact bolt, and to effect a quick closing connection between said bolt and said plug.

In testimony whereof I have signed my name to this specilication in the presence of two subscribing witnesses.

GEORG MLLER;

Witnesses KARL MLLER, ALBERT GRAU.. 

